1. Field of the Invention
The present invention relates to an electromagnet assembly for use in an electromagnetic apparatus, such as an electromagnetic clutch for use in controlling the transmission of power from an automobile engine to a refrigerant compressor in an automobile air conditioning system. More particularly, it relates to a connector in the electromagnet assembly.
2. Description of Related Art
Referring to FIG. 1, an electromagnet assembly 7, which comprises a ring member 1, a coil bobbin 3, and a ring case 4, is known in the art. Ring member 1 has a toroidal shape having a spool portion, which has an exterior open edge formed by two anuular flanges on the spool portion. Coil bobbin 3 has ring member 1 and an electrical wire 2, which is wound around the spool portion of ring member 1. Ring case 4 has an annular groove, an open edge of which is in a direction parallel to its axis. Coil bobbin 3 is inserted into the annular groove of ring case 4. An opening 4a is formed through ring case 4 adjacent to its closed end surface. A connector 5 is disposed on ring case 4 adjacent to its closed end surface and covers opening 4a. A first end 2a and a second end 2b of electrical wire 2 and a first lead 6a and a second lead 6b are joined, respectively in connector 5. Electromagnet assembly 7, for example, is used in an electromagnetic clutch 9 of a compressor 8 in an automobile air conditioning system, as shown in FIG. 2. Electromagnet assembly 7 engages compressor 8 through a ring-shaped plate 10, which is affixed to the closed end surface of ring case 4.
Referring to FIGS. 3-6, the connecting structure between connector 5 and ring case 4 and the wiring connecting structure in connector 5 is shown. As shown in FIGS. 3 and 4, connector 5 has a case 5a having a box shape including a bottom and a cap 5b, which closes an open end of case 5a. Case 5a is fixed to ring case 4 by a pair of first hooks 10a formed on ring-shaped plate 10 which engage a pair of first receiving portions 5a1 formed on case 5a. Cap 5b is fixed to case 5a by engaging a plurality of second receiving portions 5a2 formed at case 5a with a plurality of hooks 5b1 formed at cap 5b. A projection portion 5a3, which is formed on case 5a, is inserted into an opening 4a. An O-ring 11, which is disposed in an annular groove formed on case 5a, surrounds opening 4a and abuts the closed end surface of ring case 4.
As shown in FIGS. 4-6, first end 2a and second end 2b of electrical wire 2 are introduced into opening 4a through a notched portion 1a formed on a first end surface of ring member 1 and are extended into connector 5 through a pair of penetrating holes 5a4, which are formed through projection portion 5a3. A contact 12 having a first electric connection is connected to an end of second lead 6b, which is inserted into connector 5. In addition, contact 12 having a second electric connection is connected to an end of first lead 6a, which is inserted into connector 5. First end 2a of electrical wire 2 is supported between a first receiving portion formed at case 5a of connector 5 and a second receiving portion formed at contact 12, which is connected to first lead 6a. Second end 2b of electrical wire 2 is supported between a third receiving portion formed at case 5a of connector 5 and a fourth receiving portion formed at contact 12, which is connected to lead 6b. Thus, first end 2a and second end 2b of electrical wire 2 are connected to first lead 6a and second lead 6b, respectively.
Coil bobbin 3 is fixed to ring case 4 by a resin 13 (e.g., an epoxy resin), which is poured into an open end of the annular groove of ring case 4. O-ring 11, which is disposed between case 5a and the closed end surface of ring case 4, prevents resin 13 from leaking to the outside of the closed end surface of ring case 4 through the gap between projection portion 5a3 of case 5a and a surrounding wall of opening 4a, when resin 13 is poured into ring case 4.
In a known electromagnet assembly for use in an electromagnetic apparatus, it is necessary to engage the plurality of hooks 5b1 to the plurality of second receiving portions 5a2 when cap 5b of connector 5 is fixed to case 5a. Therefore, the manufacturing efficiency of fixing cap 5b to case 5a is low because this process is done by hand. Further, if the interior of case 5a does not fill with resin, water may enter into the interior of case 5a through the gap between cap 5b and case 5a, which is adjacent to an engagement portion of hook 5b1 and second receiving portion 5a2, and the insulation capabilities of connecting portions of first end 2a and second end 2b of electrical wire 2 and contact 12 may be reduced. Therefore, it may be necessary to refill the interior of case 5a with resin 13, and the manufacturing efficiency of fixing cap 5b to case 5a may be reduced.
An object of the present invention is to provide an electromagnet assembly for use in an electromagnetic apparatus which has a greater manufacturing efficiency in fixing a cap to a case of a connector, when compared with a known electromagnet assembly.
In an embodiment of the present invention, an electromagnet assembly for an electromagnetic apparatus comprises a ring member, a coil bobbin, a ring case, and a connector. The ring member comprises a tubular spool, e.g., cylindrical spool, with a pair of annular flanges projecting radially from the spool. The coil bobbin comprises an electrical wire. The electrical wire is wound around the spool between the flanges. The ring case comprises an annular groove, which has an open edge. The coil bobbin is disposed in the ring case""s annular groove. An opening is formed through the ring case adjacent to its closed end surface. The connector comprises a case and a cap. The case forms an enclosure, such as a cylinder or a box, having an open end and a bottom. The cap closes the open end of the case. The connector is disposed on the ring case adjacent to its closed end surface and covers the opening. A first end and a second end of the electrical wire, and a first lead wire and a second lead wire from an external electric circuit are connected to the first and the second ends, respectively in the connector. A projection portion is formed around a fringe portion of a first end surface of the cap and abuts an open end surface of the case. The cap is secured fixedly to the case after the projection portion is melted.
Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following description of the invention with reference to the accompanying drawings.